Fabrication of fly ash cenospheres-hollow glass microspheres/borosilicate glass composites for high temperature application

A temperature resistant buoyant material, namely, fly ash cenospheres-hollow glass microspheres/borosilicate glass (FACs-HGMs/BG) for high temperature application, was prepared through a tert-butyl alcohol-based gelcasting process, with FACs and HGMs as the fillers and BG as the matrix, respectively. The effect of FACs addition on the mechanical and high-temperature performance of the FACs-HGMs/BG composites was studied. The composites containing different amounts of FACs displayed low density (0.44–0.89 g/cm³), low Young's modulus (0.05–1.10 GPa), and relatively high compressive strength (2.78–9.75 MPa). Three stages, namely, elastic, plateau, and fracture stages, could be observed in the stress-strain curves. The compressive strength of the samples at high temperature was lower than the ones at room temperature, and the 10%FACs-HGMs/BG composite tested at 500 °C displayed a compressive strength of 6.03 MPa. The FACs-HGMs/BG composites demonstrating excellent mechanical properties both at room and high temperatures may be used as promising candidates for structural materials or temperature resistant buoyant materials in the near future.